JPH04168331A - Torque sensor - Google Patents

Abstract

PURPOSE:To enable measurement of a torque more effectively by a method wherein a conducting rubber is used to transmit a torque of a rotor thereto and a change in thickness of the rubber is detected as resistance value to allow measurement of the torque of the rotor with a plane. CONSTITUTION:Torque transmission plates 3a-3d are arranged along a circumferential surface of an inner cylinder 2. Support plates 4a-4d provided corresponding to the transmission plates 3a-3d sticking out into an internal surface of an outer cylinder 1 are arranged and conducting rubbers 5a-5d are arranged so as to be supported being sandwiched therebetweeen. When a torque is applied to an outer cylinder 2 from a roto, it is transmitted to the individual transmission plates 3a-3d to weld the rubbers 5a-5d under pressure with the corresponding support plates 4a-4d. Then, changes in thickness of the rubbers 5a-5d are detected as such in resistance value through a contact foil bonded on both sides thereof. As the rubbers 5a-5d are sandwiched between the plate-shaped members, the torque can be determined with a plane to allow the averaging of the size thereof automatically. The rubbers 5a-5d or the like are arranged at each 90 deg. thereby enabling the detection of a direction in which the torque is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a torque sensor, and more particularly to a torque sensor that detects the torque of a rotating body.

2. Description of the Related Art In general, there are cases where it is desired to measure the torque generated during rotation of a rotating shaft of a motor, a joint of a robot, or the like.

Various methods are known for measuring the torque, and one example is a method using a well-known strain gauge.

This uses a strain gauge with a size of about 10 [mmJ x 5 [++s+]], and the torque is determined by the magnitude of strain generated during rotation.

For example, as shown in FIGS. 4(a) and 4(b), four thin plates 6a to 6d are provided between the outer cylinder and the inner cylinder 2,
Strain gauges 17a-17d are attached to the surface of each thin plate. When torque is applied to the inner cylinder 2, tension is generated in each thin plate, and this tension is detected as electrical resistance by a strain gauge. Note that a tester or the like is connected to both ends of each strain gauge.

However, the above-mentioned torque measurement method uses a small strain gauge to measure the torque, so it has the disadvantage that torque can only be recognized in terms of points.

Therefore, in order to solve this problem, a method may be considered in which strain gauges are attached to several locations on each thin plate and the resistance values obtained by the strain gauges are averaged. However, this method has the drawback that the values vary depending on the direction of pasting, etc., and are not averaged correctly.

Furthermore, these methods using strain gauges require an amplifier because they measure resistance values based on minute changes in current values, and also have the drawbacks of low noise margins.

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and its purpose is to provide a torque sensor that can effectively detect the torque of a rotating body.

Structure of the Invention The torque sensor according to the present invention includes a torque transmission member that transmits the torque of a rotating body, a fixed member fixed in advance, and a conductive rubber sandwiched between the torque transmission member and the fixed member. The present invention is characterized in that the torque of the rotating body is set to 11P+ by changing the resistance value of the conductive rubber.

Example Next, the present invention will be explained with reference to the drawings.

FIG. 1 is an external view of an embodiment of a torque sensor according to the present invention, in which (a) is a front view as seen from the direction of the rotation axis of a rotating body to be measured, and (b) is a view of (a). FIG. In addition, FIG. 1(a).

In FIG. 4(b), parts equivalent to those in FIGS. 4(a) and 4(b) are designated by the same reference numerals.

In the figure, the torque sensor of the present invention uses well-known conductive rubber, transmits the torque of a rotating body to it, and detects changes in its thickness as a resistance value. In this embodiment, four conductive rubber sheets are used. A rubber plate is provided.

That is, referring to FIG. 1(a), the torque sensor of this embodiment includes an inner cylinder 2 that is connected to the rotating shaft of a rotating body, and a cylinder that is provided at 90 degree intervals along the circumferential surface of the inner cylinder 2. It is configured to include torque transmission plates 3a to 3d that transmit the torque of the rotating body.

Further, the torque sensor of this embodiment includes support plates 4a to 4d that protrude from the inner surface of the fixed outer cylinder 1 and are provided corresponding to the torque transmission plates 3a to 3d, respectively, and support plates 4a to 4d, which correspond to the torque transmission plates 3a to 3d, respectively. 3d and conductive rubber 5a to 5d sandwiched and supported by support plates 48 to 4d.

Note that the conductive rubber referred to herein is a rubber such as neorene or silicone rubber mixed with carbon black or metal powder, and electrical conduction is observed between the front and back surfaces of the rubber.

Next, the connection relationship between each torque transmission plate, support plate, and conductive rubber will be explained using FIG. 3. FIG. 3 is an enlarged view showing the bonding relationship between the torque transmitting plate, the support plate, and the conductive rubber, and shows the bonding relationship between the torque transmitting plate 3a, the support plate 4a, and the conductive rubber 5a in FIG. 1(a). ing.

In the figure, contact foils 7a and 7b for detecting the resistance value in the thickness direction are provided on both sides of the conductive rubber 5a. The contact foil 7a in contact with the conductive rubber 5a is adhered to the torque transmission plate 3a with a non-conductive rubber adhesive 8b. Further, the contact foil 7b in contact with the conductive rubber 5a is adhered to the support plate 4a with a similar non-conductive rubber adhesive 8a.

Further, a wiring wire 9a is connected to the contact foil 7a, and a wiring wire 9b is connected to the contact foil 7b. That is, the resistance value in the thickness direction of the conductive rubber 5a is measured by connecting these wiring wires 9a and 9b to a tester (not shown) or the like.

In FIG. 3, when the torque from the rotating body is transmitted to the torque transmission plate 3a, a force in the direction of the arrow Ya is applied, and the conductive rubber 5a is pressed against the conductive rubber 5a. Then, the thickness of the conductive rubber 5a becomes thinner. The decrease in resistance value due to this change in thickness is detected via the contact foils 7a and 7b as well as the wiring wires 9a and 9b using a tester (not shown) or the like. This results in
The magnitude of the torque of a rotating body such as a motor can be measured.

In addition, in the figure, since a sufficiently large piece of conductive rubber is sandwiched between plate-like members, the torque is captured in a plane, its magnitude is automatically averaged, and the average value can be detected as the resistance value. It is. Therefore, it is not necessary to provide a plurality of conductive rubbers and calculate the average value of the resistance values obtained by them. This is effective when it is desired to average and measure the torque applied to the joints of the robot.

Returning to FIG. 1, an example will be described in which four sets of these torque transmission plates, support plates, and conductive rubber joints are used.

The torque sensor shown in the figure has a structure in which a torque transmission plate, a support plate, and conductive rubber are provided every 90 degrees, as described above. In this configuration, when torque from the rotating body is applied to the inner cylinder 2, it is transmitted to each of the torque transmission plates 3a to 3d, and the conductive rubbers 3a to 3d are pressed against the corresponding support plates 4a to 4d. In this case, since each torque transmission plate, support plate, and conductive rubber are arranged every 90 degrees, it is possible to detect the direction in which torque is applied.

In other words, referring to FIG. 2, which is a schematic diagram of the operation of the torque sensor of this embodiment, when the rotating body rotates in the direction of arrow Y, a force is applied to each conductive rubber in the direction of arrows Ya-Yd. , these can be detected separately. Therefore,
If this torque sensor is provided at the joints of the robot, it is possible to detect not only the magnitude of torque but also the direction in which the torque is applied, and it is possible to make an emergency stop of the device when excessive torque is applied.

Here, as a method of coupling the rotating body to be measured and the inner cylinder, there are a method of directly connecting it to the rotating shaft and a method of applying high viscosity oil or the like to the inner surface of the inner cylinder to achieve frictional coupling. In other words, in a system in which the sensor is directly connected to the rotating shaft, there is a risk that the torque sensor may be damaged if the torque of the rotating body is excessive.

On the other hand, with a method of frictional coupling using high viscosity oil or the like, there is no risk of damage to the torque sensor even if excessive torque is applied. Therefore, various methods may be adopted depending on the object to be measured.

In addition, since this torque sensor has a simple structure, the inner cylinder that is connected to the rotating body, the outer cylinder that is fixed, the torque transmission plate, and the support plate are manufactured using metals such as iron or aluminum. , it may be molded using various resins. In particular, when molding is performed using resin, manufacturing can be done at low cost and with high production efficiency by creating a mold once, which is advantageous when manufacturing a large number of torque sensors.

Furthermore, in Fig. 2, if the direction of rotation is reversed,
A force in the opposite direction of the arrows Ya - Yd is applied to each conductive rubber, and torque can be detected as an increase in resistance value. However, in this case, it is necessary to take measures such as adhering each conductive rubber to the contact foil using a conductive adhesive or depositing a contact application material on the surface of the conductive rubber.

Furthermore, in FIG. 1(a), conductive rubber 5b,
The position of the torque transmission plate and the position of the support plate with respect to 5d may be exchanged. In this way, when the rotating body rotates in the opposite direction of the arrow Y, the conductive rubbers 5b and 5d are pressed against the support plates 4b and 4d, and when the rotating body rotates in the direction of the arrow Y, the support plates 4a and 5d are pressed against each other. The conductive rubbers 5a and 5d are pressed together at the portion 4c, and both are detected as a decrease in resistance, so there is no risk of damage to the torque sensor no matter which direction it rotates.

Furthermore, it is also conceivable to increase the number of each torque transmission plate, support plate, and conductive rubber and arrange them every 45 degrees. In addition, the number of sheets may be increased or decreased as necessary.

In addition, in this example, the case where the rotating body to be measured is coupled to the inner cylinder has been explained, but the same effect can be obtained even if the rotating body to be measured is coupled to the outer cylinder, torque is applied, and the inner cylinder is fixed. it is obvious.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention has the effect that torque can be measured more effectively, such as by being able to measure torque on a surface, by using conductive rubber and detecting torque based on changes in its thickness.

[Brief explanation of drawings]

FIG. 1(a) is a front view of a torque sensor according to an embodiment of the present invention, FIG. 1(b) is a perspective view of FIG. 1(a), FIG. 2 is a schematic diagram showing the operation of the torque sensor, and FIG. The figure is an enlarged view of the conductive rubber portion in FIG. 1, FIG. 4(a) is a front view of a conventional torque sensor, and FIG. 4(b) is a perspective view of FIG. 4(a). Explanation of symbols of main parts 1...Outer tube 2...Inner tube 3a-3d...Torque transmission plates 4a-4d...Support plates 5a-5d・・・・・・Conductive rubber

Claims (2)

[Claims] (1) It has a torque transmission member that transmits the torque of a rotating body, a fixed member fixed in advance, and a conductive rubber sandwiched between the torque transmission member and the fixed member, and the conductive rubber A torque sensor, characterized in that the torque of the rotating body is measured by a change in resistance value. (2) A cylindrical member to which the torque of the rotating body is transmitted, a plurality of torque transmitting members installed at approximately equal intervals along the circumferential surface of this cylindrical member, and a plurality of torque transmitting members fixed in correspondence with these torque transmitting members. It has a plurality of plate members, and a plurality of conductive rubbers sandwiched between the plurality of torque transmission members and the plurality of plate members, and the rotating body is A torque sensor characterized in that it measures the torque of.